Photographic objective with continuously variable focal length

ABSTRACT

A photographic objective of variable focal length consisting of four axially aligned optical members, a first collective member, a second dispersive member, a third dispersive member and a fourth collective member, with an iris diaphragm between the third and fourth member and in which for the purpose of varying the focal length the second and third members are axially adjustable relatively to each other and to the collective member. The second axially adjustable member comprises a single dispersive lens standing along by itself. A predominantly chromatically effective cemented face is provided in the dispersive third member while the dispersive second member comprises a single lens.

United States Patent [111 3,614,207

[ 72] Inventor Heinrich Basista [56] References Cited [21] A l N gfi g fi UNITED STATES PATENTS [22] May 18, 1970 3,457,003 7/1969 Macher 350/184 [45] Patented Oct. 19, 1971 Primary Examiner-John K. Corbin [73] Assignee Carl Zeiss-Stiflun g d /b/a Carl Zeis Attorney-Singer, Stern & Carlberg Heidenheim (Brena), Wuerttemberg,

Germany [32] Priority May 29, 1969 [33] Germany ABSTRACT: A photographic objective of variable focal [31] P 27 278-7 length consisting of four axially aligned optical members, a

first collective member, a second dispersive member, a third dispersive member and a fourth collective member, with an iris diaphragm between the third and fourth member and in [54] PHOTOGRAPHIC OBJECTIVE WITH CONTINUOUSLY VARIABLE FOCAL LENGTH which for the purpose of varying the focal length the second zchims4nnwins Figs and third members are axially adjustable relatively to each [52] U.S.Cl 350/184, ,other and to the collective member. The second axially ad- 350/214 justable member comprises a single dispersive lens standing [51] Int. Cl ..G02b 15/14 along by itself. A predominantly chromatically effective ce- [50] Field of Search 350/184, mented face is provided in the dispersive third member while 186 the dispersive second member comprises a single lens.

PATENIEUnm 19 I911 SHEET 10F 2 PHOTOGRAPHIC OBJECTIVE WITH CONTINUOUSLY VARIABLE FOCAL LENGTH The invention relates to photographic objectives of variable focal length.

This type of objectives comprise four axially aligned optical members of which the first one A possesses a collective power of refraction, the second member B a dispersive power of refraction, the third member C a dispersive power of refraction, and the fourth member D a collective power of refraction. A change in the focal length is effected by axially displacing the two dispersive members B and C along the optical axis of the objective relatively to each other and relative to the collective members A and D. The collective fourth member D comprises a lens having a collective power of refraction, a splitting cube and a multilens basic objective having a collective power of refraction. The splitting cube is arranged directly in front of an iris diaphragm in the optical path of the light rays and has the purpose to direct a portion of the beam of light to the finder arranged in the camera.

The object of the invention is to develop such a type of photographic objective for a size 4.22 5.69 mm. with a small optical expenditure and to obtain at a relatively small length of construction and a small diameter of the front lens an expansion range of aboutlZ; fZBO mm.There are variable objectives known which have a similar construction of which the second member 8 is provided with a chromatically acting cemented face. The objectives of the present invention do not have this feature. In the objectives made in accordance with the invention the predominantly chromatically effective cemented face is arranged in the dispersive third member C, while the dispersive second member B comprises a single lens only.

In accordance with the present invention the refractive powers of the members B and C are so distributed that the variable air space d in the wide angle position with respect to all other focal length adjustments is the largest. In this arrangement it is possible to obtain the required chromatic correction with a cemented face in the dispersive third member C. The displacement of the cemented face from the second member B into the third member C makes it, however, possible to obtain, in accordance with the present invention, a reduction in the exterior dimensions, namely of the front lens diameter and the length of the objective.

IN THE DRAWINGS FIG. 1 illustrates diagrammatically in axial section an objective of the invention as given in table I in a position for f= 21.55 mm.,

FIG. 2 is a graph illustrating the variable air spaced d d and a, in relation to the focal length f of the objective;

FIG. 3 illustrates diagrammatically in axial section an objective of the invention as given in table 11 in a position for F 22.07 mm; and

FIG. 4 is a graph illustrating the variable air spaces (1,, d, and d. in relation to the focal length f of the objective shown in FIG. 3.

In an objective according to the following table I, all the above requirements are met. The described objective is corrected for the relative aperture f:l.9.

TABLEI Thicknesses Lenses Radii, mm. and separa- 1'1 V tions, mm.

1' 1483 19 LI 1 u 868 1 6.0 1.62299 58.06

r -l l9.63

1.70; 9.75 d 17.80 22. 2 1.70 +127'72l d 10 1620 11 60 3 111 11 18.1 1 10.86 d 5.10 g 3. 3 2.50 r 1 1.853

Table l Ct ntinued thicknesses Lenses Radii, mm. and separb d d tions, mm.

LIV r 8 171 6 1.517112 5 L1 1 27 7 2.0 1.71736 29,51

7-59 r 5.30 l 5'33 1 20.982 Ln 1 6 1 938 G9 1 60.33

0 0) 10 .7 LV'II r12 m 11 6.0 1.51680 6 1.17 13 8 9123 (112 (mapm'aflm P Lvm 111 029 "11300 53.83

i 1 -1 0. 1 20.2 11 In I 6 8 53 1 d15 7 2 .08

1 16 0.6 r 18.171 Lx r 18 171 1! LYMOO 411. 77

The values in this table I for the variable air spaces d d and d, relate to the different positions of the respective members for the different focal lengths of the objective.

l f v The focal lengths of individual members are: f,4=+70.58

TABLE I:

Thickn Lenses Radii, 111111. and 00:1 1'1 v tions, 111111.

a 1. Ln r 470.3 12 2 1 781m) 26 08 0.8 12.606; (1 2 1. 111 3%.157 LI n I 76.625 3 .531

0 1.0 LIV r 1 1.6 12 6 1 71300 53 83 d I 2. L r8 I 71.27 7 5 1 78 t70 26 08 & 8.52 1; 8.125 (I I 6.1"10 i r 33.2 11

0 0.8 11 m Lvn r m a 5.0 1.51680 6 1.17

Tablefll-Cominued Table l -Cn11nued Thicknesees Thlcknesses Lenses Radii, mm. and separa- 1'1 v Lenses Radii, mm. and separa- 11 v tions, mm. tions, mm. a .0 1.620 11 60. 11 2.0 1.71736 29.51 LVIII 62.19 1 13 33 5 Lv r -262.27 7

0 1.5 E -3 r 10.517 7.59 t. 0 1.0 1.80518 25. 13 6 5.30

616 1.5 1.00 g d 0 1 620 11 60 a I'VI r9 3 20882 a 2 3 1 2 11 69 33 LX r11 12.959 17 3' I 3 10 10 6L938 9 i I 0 0.1 1o r 2 1.758 11 m L 19 1 4.0 1.620 11 60.33 d 6.0 1.51680 6 1.17

X1 r 15.178 9 12 w 1:1 5.2 (Diaphragm Space) r 5.9123 The values given in this table I] for the variable air spaces d 15 0/111 r1 95 02g 613 2.7 1.71300 53.83 d and d relate to the different focal lengths of the objective. 2o 0 1 0J1 1, 15 11 3.2 1.701170 26.08 0.80 29.906 0.524 1025 r 5 8.534 12.606 18.500 8.l25 14.58 r I 18 171 16 24.411 8.679 6.140 22.07 LX 17 d1, 1111,00 31.151 4.670 3.403 29.19 18.171 34.531 3.500 1.200 34.30

The focal lengths of the individual members are: 2. A photographic objective with continuously variable focal length having four axially aligned optical members, a fifirst collective member, a second dispersive member, a third f 03 dispersive member and a fourth collective member, in which E- the change of the focal length is effected by axially displacing -35 the two dispersive members relatively to each other and relatively to said two collective members, wherein the improvef,,=-+-23.10 ment comprises that said second dispersive member consists in the tables I and II the lenses are designated with L, the of a Smgle 9 standmg by itself that said third dispersive radii with r, the axial thicknesses and air separations with d, member contains a chromaucany effect've P the index of refraction with "d, the Abbe numbers with vd for mented face, that the variable air space (4.) between the third the d-line of the spectrum, and the distance between the rear and fourth member m the angle Posmon "femnce lens and the image or intercept length with s.

It should be noted that also other objectives whose finished data do not agree accurately with the values given in the above tables may possess a substantially similar good condition of correction, but it is recommended that the finished data conform as closely as possible to the data in these tables.

What I claim is:

1 A photographic objective with continuously variable focal length having four axially aligned optical members, a first collective member, a second dispersive member, a third dispersive member and a fourth collective member, in which the change of the focal length is effected by axially displacing the two dispersive members relatively to each other and relatively to said two collective members, wherein the improvement comprises that said second dispersive member consists of a single lens standing by itself, that said third dispersive member contains a predominantly chromatically effective cemented face, that the variable air space (11 between the third and fourth member in the wide angle position with reference to the other focal length positions is the largest and that the finished data of the objective comply substantially with the data given in the following table.

to the other focal length positions is the largest and that the finished data of the objective comply substantially with the data given in the following table.

TABLE 11 Thicknesses Lenses Radii, mm. and separan v tions, mm.

d 10.0 1.62280 56.90 LI r w 655 1 L 2 170's a 1.6 1.78 170 26.08

1 2-21.11 r 15.8 19 r 11 6A2 1 1.0 1.71300 53.83 L 7 7 a 2.5 1.78 170 26.08

8425i 6 6.1 10 i i383 r9 3325 a 3 0 620 1 6 r m 11 0.8 Lvn m a 5.0 1.51680 6 1.17

a 1.5 r 10.517 I r 1 F 16 669 11.0 1.80518 25. 13

a n 1. r -365.15 16 5 1. 0 3.0 1.620 11 60.33

(1 I 0.1 r- I 2R.758 r. 19 15 178 0 1.0 1.620 11 60.33 

1. A photographic objective with continuously variable focal length having four axially aligned optical members, a first collective member, a second dispersive member, a third dispersive member and a fourth collective member, in which the change of the focal length is effected by axially displacing the two dispersive members relatively to each other and relatively to said two collective members, wherein the improvement comprises that said second dispersive member consists of a single lens standing by itself, that said third dispersive member contains a predominantly chromatically effective cemented face, that the variable air space (d8) between the third and fourth member in the wide angle positiOn with reference to the other focal length positions is the largest and that the finished data of the objective comply substantially with the data given in the following table.
 2. A photographic objective with continuously variable focal length having four axially aligned optical members, a first collective member, a second dispersive member, a third dispersive member and a fourth collective member, in which the change of the focal length is effected by axially displacing the two dispersive members relatively to each other and relatively to said two collective members, wherein the improvement comprises that said second dispersive member consists of a single lens standing by itself, that said third dispersive member contains a predominantly chromatically effective cemented face, that the variable air space (d8) between the third and fourth member in the wide angle position with reference to the other focal length positions is the largest and that the finished data of the objective comply substantially with the data given in the following table. 